Area Forecast Discussion
Issued by NWS Honolulu, HI

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FXHW60 PHFO 220630
AFDHFO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
830 PM HST SUN SEP 21 2014

.SYNOPSIS...
LIGHT WINDS WILL CONTINUE TONIGHT WITH A FEW SHOWERS STILL POSSIBLE
THROUGH THE EVENING HOURS...ESPECIALLY OVER LEEWARD BIG ISLAND
AREAS...AS LINGERING MOISTURE REMAINS IN PLACE. THE TRADES WILL
GRADUALLY RETURN THROUGH MID WEEK AND BRING SOME RELIEF
FROM THE HUMID AND MUGGY CONDITIONS...WITH SHOWERS BECOMING MORE
FOCUSED OVER WINDWARD AND MOUNTAIN AREAS. A WETTER TRADE WIND
PATTERN IS EXPECTED FOR THE SECOND HALF OF THE WEEK.

&&

.DISCUSSION...
REMNANT CONVECTION FROM THE AFTERNOON SEA BREEZES IS STILL
GENERATING SHOWERS OVER PORTIONS OF THE BIG ISLAND WITH THE MOST
ACTIVE RAINFALL AFFECTING THE SE SLOPES OF MAUNA LOA FROM WOOD
VALLEY TO NAALEHU.

A TROPICAL DISTURBANCE A COUPLE HUNDRED MILES WSW OF THE BIG ISLAND
IS KEEPING ENHANCED LOW LEVEL MOISTURE LINGERING AROUND THE BIG
ISLAND AND ADJACENT COASTAL WATERS. ALSO...WATER VAPOR SATELLITE
IMAGERY DEPICTS AN UPPER LEVEL TROUGH ALIGNED FROM SW TO NE BETWEEN
MAUI COUNTY AND THE BIG ISLAND. THESE FEATURES ARE STILL PROVIDING
FAVORABLE ATMOSPHERIC CONDITIONS FOR SPORADIC THUNDERSTORM
ACTIVITY...MAINLY AROUND THE KAU DISTRICT. CONVECTION OVER THE
SMALLER ISLANDS IS NOW SUBSIDING...BUT THERE IS ENOUGH LINGERING
MOISTURE TO GENERATE ADDITIONAL SHOWERS THIS EVENING. THEN SKIES
SHOULD START CLEARING OUT AS LAND BREEZES DEVELOP OVERNIGHT.

WINDS IN GENERAL WILL REMAIN THROUGH EARLY MON AS A STATIONARY
DISSIPATING SFC FRONTAL BOUNDARY ABOUT 400 MILES N OF THE ISLAND
CHAIN LINGERS. THIS FEATURE WILL GRADUALLY BE REPLACED BY A
BUILDING HIGH PRESSURE SYSTEM NW OF THE ALOHA STATE...WHICH WILL
BRING INCREASING PRESSURE GRADIENTS ACROSS THE AREA AND A RETURN TO
A MORE TYPICAL TRADE WIND FLOW DURING THE FIRST HALF OF THE WORK
WEEK. AS THE TRADES BUILD UP...EXPECT A GRADUAL RELIEF FROM THE
MUGGY AND HUMID CONDITIONS FROM THE LAST SEVERAL DAYS. THE TRADES
WILL ALSO SHIFT THE FOCUS OF SHOWER ACTIVITY BACK TO WINDWARD AND
MOUNTAIN AREAS.

GLOBAL MODELS SHOW FAIR AGREEMENT IN DEPICTING A FRONTAL BOUNDARY
MOVING INTO THE AREA FROM THE N WITH AN ASSOCIATED BAND OF MOISTURE
REACHING THE ISLANDS FROM LATE WED AND INTO THU. THIS WILL BRING A
RATHER WET TRADE PATTERN DURING THE SECOND HALF OF THE WEEK. TIMING
OF THIS EVENT IS STILL BEING EVALUATED...BUT IF THE MODELS ARE
CORRECT THIS BAND OF MOISTURE COULD LINGER ACROSS THE ISLANDS
THROUGH THE WEEKEND AND EVEN INTO EARLY NEXT WEEK. THUS...THERE IS A
POSSIBILITY THAT EXTENDED PERIODS OF VERY WET CONDITIONS OVER
WINDWARD AND MOUNTAIN AREAS MAY AFFECT THE ISLANDS DURING THE LATER
PART OF THE WEEK.

&&

.AVIATION...
CONVECTIVE ACTIVITY ACROSS THE ISLANDS IS NOW DIMINISHING. BRIEF
MVFR CONDITIONS IN PASSING SHOWERS WILL REMAIN...MAINLY FOR WINDWARD
AND MAUKA AREAS TONIGHT. TRADE WINDS ARE EXPECTED TO GRADUALLY
RETURN TOMORROW...AND SHOWER ACTIVITY WILL MAINLY FOCUS ALONG
WINDWARD AND MAUKA AREAS WITH A FEW CLOUDS DEVELOPING OVER LEEWARD
AREAS.

&&

.MARINE...
INCREASING TRADES COULD BRING SPEEDS CLOSE TO SMALL CRAFT ADVISORY
LEVEL OVER THE TYPICALLY WINDIER WATERS AROUND THE BIG ISLAND AND
MAUI COUNTY STARTING TUESDAY.

SURF HEIGHTS ARE EXPECTED TO REMAIN NEAR BACKGROUND LEVELS THROUGH
MOST OF THE WEEK. A SLIGHTLY HIGHER SWELL OF AROUND 4 FEET IS
EXPECTED FROM THE NNE THURSDAY THROUGH SATURDAY. A MODERATE SSW IS
DUE NEXT WEEKEND.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$

REYNES






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